This research project is concerned with the development and validation of more refined methods of measuring the behavior of newborn infants and of describing individual differences in infants as they affect the interaction of the infant with people and with the environment. During this year the NBAS-K, Neonatal Behavioral Assessment Scale with Kansas Supplements, will be tested on a sample of 200 infants and a selected number of those infants will be observed in the nursery, in mother-infant interaction in the hospital and at home, and in interaction with non-social environmental stimulation. These observations will be related to subsequent developmental outcome. The overall objective of the research is to develop more refined indices that identify individual differences in infants and environments and the interactions that foster positive developmental outcome and those that do not foster positive development so as to be able to develop specific criteria for intervention programs.